JP3686186B2 - Mold for resin molding and molding method using the same - Google Patents

Description

【００５３】
［実施例５〜６、比較例３〜４］
実施例１、３及び比較例１、２で得られた成形品を試験片として上記（３）の評価を行った。
【００５４】
実施例５、６では、それぞれ実施例１、３で得られた成形品を試験片とした。何れの試験片に於いても、成形品表面全体に渡って凹凸形状が均一に転写されており、外観状態の判定は○であり非常に好ましい結果であった。
【００５５】
比較例３では、比較例１で安定して得られた成形品を試験片とした。離型不良を伴わず安定して成形が行えたにもかかわらず、凹凸形状の転写が充分でないため不均一な光散乱に因る模様が生じ、外観状態は×と判定した。
【００５６】
比較例４では、比較例２で得られた成形品を試験片とした。金属薄板の熱膨張に伴う皺模様が転写されており、また凹凸形状はほとんど転写されておらず、外観状態の判定は×とした。
【００５７】
［実施例７、比較例５］
実施例７では実施例１で得られた成形品を試験片とし、比較例５では比較例１で得られた成形品を試験片として上記（４）の評価を行い、表２に示す結果を得た。
【００５８】
実施例７では、輝度最大値は７５０ｎｔ、輝度均斉度は０．７２と何れも高い値を示し、均一で明るい面照明光源装置を得る事ができ非常に好ましい結果となった。
【００５９】
比較例５では、輝度最大値は３４０ｎｔ、輝度均斉度は０．３５と何れも低い値を示し、面照明光源装置として充分な性能が得られず好ましくない結果となった。
【００６０】
【表２】

【００６１】
【発明の効果】
本発明の金型を用いる事により、微細な凹凸形状のパターンを要求に応じて任意に変更する事が可能で、かつ該凹凸形状を効果的に転写させた各種熱可塑性樹脂成形品を工業的に安定して生産する事ができる。
【図面の簡単な説明】
【図１】本発明に於ける金型を構成する吸引孔の形状の一例を示す断面図である。
【図２】本発明に於ける金型の概念図の一例である。
【図３】本発明の実施例に用いた金型の構成図である。
【図４】本発明の実施例に用いた金型に於ける吸引孔の形状及び配置の説明図である。
【図５】本発明の実施例に用いた面照明光源の輝度分布測定方法の概念図である。
【符号の説明】
１１ 金属薄板
２１ キャビティ部
２２ 枠体
２３ 吸引孔を有する入れ子
３４ ゲート位置
３５ パーティング面
３６ 板状偏肉成形品
４２ 排気系流路
５１ 反射フィルム
５２ 拡散フィルム
５３ 冷陰極管
５４ 輝度計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold for imparting a fine uneven shape to the surface and a molding method using the mold in injection molding using various thermoplastic resins. In particular, it is suitable for injection molding of a light guide plate for a surface illumination device.
[0002]
[Prior art]
Injection molding has the greatest advantage in obtaining a molded product having a complicated shape in a single molding, and by using this advantage, it is possible to give all kinds of surface shapes.
[0003]
As an example of a molded product having a fine concavo-convex shape on the surface, there is a light guide plate for a surface illumination light source that is devised so as to cause light scattering by a texture pattern in which the concavo-convex shape is regularly arranged to emit light uniformly. In such a light guide plate for a surface illumination light source, the performance of the surface illumination light source can be adjusted by changing the type of the embossed pattern, that is, the regularity, shape, and size of the arrangement of the uneven portions. It is effective for.
[0004]
As a method for obtaining a light guide plate for a surface illumination light source in which a concavo-convex light scattering portion is formed on the surface by applying these texture patterns at the time of injection molding, for example, JP-A-4-355409 has a shape pattern. Japanese Patent Application Laid-Open No. 7-159623 discloses a method of obtaining a light guide plate molded product having a surface shape by sandwiching a transfer sheet in a molding die and performing injection molding and peeling the sheet from the obtained molded product. Discloses a method for obtaining a light guide plate molded product using a mold in which a large number of recesses having an arbitrarily changed area and a roughened bottom surface are formed.
[0005]
[Problems to be solved by the invention]
According to the method of Japanese Patent Laid-Open No. 4-355409, there is no description about the thermal characteristics and fixing method of a transfer sheet that gives an uneven shape, and the transfer sheet undergoes thermal deterioration or misalignment during molding, resulting in a desired uneven shape. There is a possibility that the assigned molded product cannot be obtained efficiently. In addition, a process of peeling the transfer sheet is necessary to obtain an integrally molded product with an uneven shape. Therefore, it cannot be said that it is an industrially stable production method.
[0006]
According to the method disclosed in Japanese Patent Laid-Open No. 7-159623, in order to control the luminance distribution of the light emitting surface in order to satisfy various required characteristics for the surface illumination light source, a mold having a concavo-convex pattern is prepared as needed. This requires a lot of time and cost, and is not suitable as an industrially stable production method.
[0007]
A common problem in the above-described prior art is that an integrally molded product in which a fine uneven shape is transferred to the surface can be produced industrially stably even if the uneven shape pattern is arbitrarily changed as required. It is not a method.
[0008]
If a thin metal plate material is formed with irregularities on the surface by a method such as cutting or etching, and the metal plate is fixed inside the mold cavity and injection molding is adopted, in one injection molding process It is possible to efficiently obtain an integrally molded product in which the uneven shape is transferred to the surface. In addition, since a thin metal plate material is used, an arbitrary concavo-convex pattern can be easily formed and can be carried out in a short time and at a low cost. Further, the metal thin plate can be arbitrarily replaced with a desired uneven shape pattern, and the above problems can be solved.
[0009]
In order to stably maintain the transferability of the fine unevenness in the molded product obtained by using the above method, conditions such as high injection pressure and holding pressure or high mold temperature are usually used. It is done. Increasing the injection pressure and holding pressure improves the transferability of the concavo-convex shape to the molded product. However, as the concavo-convex shape becomes finer, the adhesion of the molded product to the metal thin plate surface increases, and the metal thin plate is released during mold release. Deforms and a new problem arises that a good molded product cannot be obtained. Also, if the mold temperature is increased to such a degree that a stable transfer effect can be obtained, the difference between the thermal expansion coefficient between the metal sheet material having a concavo-convex shape on the surface and the matrix material holding it will cause a gap between the metal sheet and the mold. There arises a problem that gaps are generated and conversely the transferability of the uneven shape is remarkably lowered.
[0010]
The object of the present invention is to use a mold in which a thin metal plate having a fine uneven shape is fixed on the surface on which the mold cavity is formed, and the uneven pattern can be arbitrarily changed as required. In addition, an object of the present invention is to provide a method for industrially and stably producing various thermoplastic resin molded products to which the uneven shape is effectively transferred, and the molded products thereof.
[0011]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-described problems, the present inventors have found that a thin metal plate having a fine uneven shape is installed on a nesting surface having suction holes, and a specific position of the thin metal plate is defined by a frame. The present inventors have found an injection molding method for industrially stably obtaining a molded product having excellent surface unevenness transferability in various thermoplastic resins by using a mold having a sandwiched structure.
[0012]
That is, according to the first aspect of the present invention, a thin metal plate having a fine concavo-convex shape on the surface forming the mold cavity is provided on the surface of the nest having suction holes, and the outer peripheral portion of the thin metal plate on the resin gate side is provided. A mold for resin molding characterized in that a metal thin plate is installed on the surface of a nest so that the resin flow end portion side at the other end can be moved so as to be sandwiched between frames.
[0013]
In the first mold of the present invention, the ratio a / t between the suction hole diameter a and the metal sheet thickness t in the nesting is preferably in the range of 0.05 to 5. .
[0014]
The second aspect of the present invention is a method for molding a thermoplastic resin that is injection-molded using the above mold.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0017]
In the present invention, suction of a thin metal plate having a fine uneven shape can be performed by connecting the suction hole to a general oil rotary vacuum pump or the like and exhausting it.
[0018]
When the suction hole has a shape in which the suction-side diameter a and the exhaust-side diameter b are different, the load applied to the vacuum pump during evacuation can be suppressed, and suction can be performed uniformly in each suction hole. This is preferable because it is possible. For example, a shape in which the diameter a and the diameter b change discontinuously as shown in FIG. 1A, a shape that changes continuously in a straight line or a curve as shown in FIG. Is given as an example. In particular, in the shape in which the diameter a and the diameter b change discontinuously in a step shape shown in FIG. 1A, the ratio of the depth La of the diameter a to the depth Lb of the hole of diameter b. Changing La / Lb is preferable in that the resistance applied to the exhaust pump during suction can be reduced, and at the same time, processing is easy. A value of La / Lb is preferably in the range of 0.01 to 2 because the resistance during suction is small. If the value of La / Lb is within this range, the shape of each suction hole may be arbitrarily changed depending on the position in the product surface area.
[0019]
There is no particular limitation on the number of suction holes. Theoretically, the number should be one or more, but it is necessary depending on the roughness of the contact surface between the suction holes and the thin metal plate and the degree of leakage in the exhaust passage. Since the number of suction holes to be different is different, it is usually preferable to have five or more suction holes.
[0020]
The arrangement of the suction holes is large in the region of the resin injection side into the mold cavity on the metal thin plate surface, that is, the region on the resin gate portion (hereinafter referred to as “gate portion”) side. It is particularly preferable when the arrangement is uneven such that there is little in the region. Such a gate portion is usually arranged not on the product surface but on the outer periphery of the product surface.
[0021]
FIG. 2A shows an example in which a product having a square projection view is obtained by filling a resin from the gate portion GA, and the metal thin plate 11 has a frame 22 at the outer peripheral portion YA on the gate portion GA side. The outer peripheral portion ZA on the resin flow end portion side is movable.
[0022]
In the example shown in FIG. 2A, the separation between the outer peripheral portion YA on the gate portion GA side and the outer peripheral portion ZA on the resin flow end portion side is from the gate portion GA to the resin flow end portion ( This is performed with an arc XA in which the distance that is half the distance to PA1 and PA2) in the figure is drawn as a radius.
[0023]
FIG. 2B shows an example in which a product whose projection is rectangular is obtained by filling the resin from the gate parts GB1 and GB2, and the metal thin plate 11 has two outer peripheral parts on the gate part side. The outer peripheral portion ZB on the resin flow end side is movable by being sandwiched and fixed by the frame body 22 at YB.
[0024]
In the example shown in FIG. 2B, the separation between the outer peripheral portion YA on the gate portion side and the outer peripheral portion ZA on the resin flow end portion side is centered on each gate portion from the gate portion to the resin flow end portion (in the figure). PB1 and PB2) in the arc XB drawn with a radius as a half distance.
[0025]
In the present invention, the setting of the fixed region and the free region on the outer peripheral portion of the metal thin plate is not limited to the above two examples, and can be appropriately set according to the planar shape of the product and the position of the gate portion, The shaped thin metal plate is sandwiched and fixed completely by the frame at the outer peripheral portion on the gate portion side, and even if the thin metal plate is thermally expanded or contracted at the other outer peripheral portion on the resin flow end portion side It should be movable in a direction parallel to the resin flow direction.
[0026]
In order to be able to move the outer peripheral portion of the metal thin plate on the resin flow end portion side in a direction parallel to the resin flow direction, it can be realized by providing a gap between the metal thin plate and the frame. Specifically, the vertical gap between the frame and the metal sheet surface is 0.02 to 0.05 mm, and the parallel gap between the frame and the metal sheet surface is 0.05 to 0.5 mm. Is preferred.
[0027]
If the gap between the frame and the metal thin plate surface is within the above range, it is preferable in that the metal thin plate can move and does not cause burrs or the like in the molded product. When the resin is filled into the mold cavity, the metal thin plate is thermally expanded by the heat of the molten resin, and is repeatedly deformed such that the metal sheet contracts when cooled to the solidification temperature of the resin. When the entire outer periphery of the metal thin plate is completely fixed, a saddle-like appearance defect due to thermal deformation occurs on the surface of the metal thin plate, while when the entire outer periphery can be moved, the displacement of the metal thin plate occurs, In either case, it is not preferable because it causes a transfer defect or an appearance defect of the uneven shape on the surface of the molded product.
[0028]
In the example shown in FIG. 2A, the outer peripheral portion YA of the thin metal plate 11 is sandwiched by the frame 22 without a gap, and the other outer peripheral portion ZA is perpendicular to the frame and the thin metal plate surface. The cavity portion 21 is provided with a gap of 0.04 mm as a gap. In the figure, D is a gap in the direction parallel to the frame and the thin metal plate surface. In the example shown in FIG. 2B, the outer peripheral portion YB of the thin metal plate 11 is sandwiched by the frame 22 without any gap, and the other outer peripheral portion ZB is 0 as the vertical gap between the frame and the thin metal plate surface. .05 mm spacing is provided.
[0029]
In the present invention, it is preferable that the ratio a / t between the thickness t of the thin metal plate having fine irregularities and the diameter a of the suction hole is in the range of 0.05 to 5. If the value of a / t is within this range, the deflection of the thin metal plate at the position of the suction hole with respect to the filling pressure of the molten resin can be ignored, which is preferable in that the appearance defect of the molded product does not occur.
[0030]
The fine uneven shape on the surface of the thin metal plate used in the present invention can be observed with a commercially available optical microscope or electron microscope. From the obtained observation image, it can be determined whether the fine concavo-convex shape is constituted by a regular arrangement of concavo-convex shape units or the surface is unevenly uneven.
[0031]
When the concave / convex shape units are regularly arranged to form a fine concave / convex shape, the structural unit may be a cubic shape, a rectangular parallelepiped shape, a cylindrical shape, an elliptical cylindrical shape, a prism shape, a spherical shape, an aspherical shape, or the like. An example is given. Examples of the arrangement of these shapes include dot-like, linear, and curved arrangements, for example.
[0032]
The height of the concavo-convex shape and the arrangement interval may be arbitrarily changed in the vertical or horizontal direction. The height and interval can be visually measured from an observation image of an optical microscope or an electron microscope.
[0033]
Moreover, it is also preferable that the fine uneven surface is a satin-like surface, and it is preferable that it is in the range of 1 to 100 μm when the maximum height (Ry) of the surface roughness is measured by JIS B0601-1994 method. The surface roughness of the textured surface can be measured using a commercially available surface roughness meter.
[0034]
In order to obtain a metal thin plate with a fine uneven shape used in the present invention, an etching method, a cutting method, an electric discharge method, or an electroforming method or a casting method using a metal thin plate material are used. Known techniques can be used.
[0035]
The etching method is a method in which a concavo-convex shape is formed in advance on a photographic film or the like, a mask corresponding to the concavo-convex shape is formed on a metal thin plate surface by a photoresist method, and then the metal thin plate is etched with a chemical.
[0036]
The electroforming method is a method of first forming a concavo-convex shape by etching with a master having a desired concavo-convex shape on the surface of a metal material such as steel, aluminum or brass, or a surface of a smooth plate formed of a thermoplastic resin. An electroforming mold for electroforming is prepared by a method of cutting a shape to form a desired concavo-convex shape. Next, the electroplating is immersed in an electrodeposition bath, and a metal plating is formed on the surface in a thickness range of 0.1 to 1 mm. Laminate with. After that, the electric mold is taken out from the electrodeposition tank, and the laminated plating portion is peeled off from the electric mold to obtain a laminated plating portion on which the uneven shape of the surface of the electric mold is transferred. It is the method used as.
[0037]
The second aspect of the present invention is a method of molding a thermoplastic resin that is injection-molded using the above-mentioned mold, and the shape and thickness of a molded product obtained by such a molding method are not particularly limited, but the thickness is 0.1 to 10 mm. More preferably, a plate-shaped molded product within a range of 0.5 to 5 mm is preferable. If it is within this thickness range, it may be an uneven shape in which the thickness changes.
[0038]
Specific examples of the molded product having a fine uneven shape on at least one surface obtained by the molding method include a light guide plate for a surface illumination light source. A surface illumination light source device used for a liquid crystal display device or the like has a particularly high demand for brightness, and the light guide plate used is also required to have a high transferability of a fine uneven shape. The light emission efficiency on the surface of the light guide plate can be increased by transferring the fine uneven shape on the thin metal plate to at least one surface of the light guide plate, and the brightness of the surface illumination light source device can be improved by optimizing the fine uneven shape pattern. Can be made uniform without decreasing. According to the present invention, a light guide plate for a surface illumination light source having an irregular pattern arbitrarily changed according to demand can be produced industrially and stably even under molding conditions in which the irregular shape is transferred. Can do.
[0039]
The thermoplastic resin used in the present invention is specifically methacrylic resin, polycarbonate resin, polystyrene, rubber reinforced polystyrene, acrylonitrile-butadiene-styrene copolymer, styrene-methyl methacrylate copolymer resin, styrene-butadiene copolymer resin, Examples include polyethylene, polypropylene, amorphous polyolefin resin nylon 6, nylon 66, and modified polyphenylene ether. Those preferably employed are methacrylic resin or polycarbonate resin. Particularly preferred is methacrylic resin.
[0040]
Examples of the methacrylic resin include resins mainly composed of methyl methacrylate, which include a homopolymer of methyl methacrylate, or methyl methacrylate and methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, acrylonitrile, acrylic Acid, methacrylic acid, vinyl pyridine, vinyl morpholine, vinyl pyridone tetrahydrofurfuryl acrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylacrylamide, 2-hydroxy acrylate, ethylene glycol monoacrylate, glycerin monoacrylate, maleic anhydride A copolymer with at least one of copolymerizable monomers such as acid, styrene, or α-methylstyrene, and heat-resistant acrylic Butter, and the like low hygroscopicity acrylic resin. These may be used alone or in a blend. In order to maintain transparency and have impact resistance at the same time, an impact-resistant acrylic resin is used, and rubber elastic bodies thereof are disclosed in JP-A-53-58554, JP-A-55-94917, and JP-A-61-32346. No. gazette and the like. Briefly, it is a multistage polymer produced by a multistage sequential polymerization method in which an elastic layer and an inelastic layer are alternately formed around an acrylic polymer core material.
[0041]
【Example】
Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, the metal mold | die used by each Example and the comparative example, molding conditions, evaluation of a molded article, and a test method are as follows.
[0042]
(1) Fabrication of a mold in which a metal thin plate having a fine concavo-convex shape is fixed. As a metal thin plate having a concavo-convex shape on the surface, a rectangular parallelepiped shape unit is formed in two different thicknesses of 0.3 mm and 0.05 mm. There were prepared a total of four types of arrangements and prism arrangement units arranged in a straight line. As shown in FIG. 3A, the shape of the metal thin plate is a rectangle of 208 × 158 mm. As shown in the cross-sectional view on the straight line connecting P1 and P2 in the drawing (FIG. 3B), a nesting 23 having a suction hole is provided on the back surface of the thin metal plate 11, and the outer circumference of the thin metal plate 11 is 4 mm. The width portion is sandwiched between the frame bodies 22. Two types of frame 22 were prepared, one having a shape in which the metal thin plate can be moved in the flow direction at the flow end portion of the resin, and the other having a shape in which the entire outer periphery of the metal thin plate is completely fixed without a gap. In the drawing, there is no gap between the outer peripheral portion indicated by R1 and the thin metal plate 11, and the outer peripheral portion indicated by R2 has a shape in which an interval of 0.05 mm is provided in the direction perpendicular to the surface of the thin metal plate 11. The frame body 22 shown in FIG. 3 has no gap with the thin metal plate 11 at the outer peripheral portion indicated by R1 in the drawing, and the outer peripheral portion indicated by R2 has an interval of 0.05 mm in the direction perpendicular to the surface of the thin metal plate 11. It has a provided shape, and when the resin is filled, the metal thin plate 11 can move in the flow direction at the flow end portion. In addition, a gap of 0.1 mm is provided between the frame body and the metal thin plate surface in the parallel direction. Two types of inserts 23 for sucking the metal thin plate 11 were prepared, one having a suction hole diameter a of 0.3 mm and one having a diameter of 1.0 mm, and these were made the same size so that they could be exchanged at any time. . The shape of the suction hole is stepped as shown in FIG. 4A, the diameter b on the exhaust side is 3 mm, the hole depth La of the diameter a is 3 mm, and the hole depth Lb of the diameter b is the ratio La of La and Lb. / Lb was changed depending on the position of the suction hole so that it was within the range of 0.1 to 0.4. In addition, the suction holes are arranged as shown in FIG. 4B, and on the exhaust side, all the suction holes are joined by a groove having a depth of 1 mm to form an exhaust system flow path 42, which is connected to a vacuum pump. The air was exhausted while maintaining a degree of vacuum of 0.02 Torr. In the mold obtained as described above, it is possible to obtain a plate-shaped uneven-thickness molded product (projection surface is a rectangle of 200 × 150 mm) in which the uneven shape of the metal plate is transferred to the surface.
[0043]
(2) Molding conditions for an injection molded product having fine irregularities on the surface The mold obtained in (1) above is attached to an injection molding machine (SG-100 manufactured by Sumitomo Heavy Industries, Ltd.), and methacrylic resin (manufactured by Asahi Kasei Kogyo) And injection molding was performed using a trade name Delpet 80NH). The molding temperature was 240 ° C., the mold temperature was 70 ° C., the injection pressure was 175 MPa, and the holding pressure was 85 MPa.
[0044]
(3) Evaluation of appearance of molded product The molded product obtained by the above method (2) was visually observed to observe the transferability of the surface uneven shape. When surface unevenness due to non-uniform transfer was observed, it was judged as x, and when transfer was made uniform and surface unevenness was not observed, it was judged as ◯.
[0045]
(4) Luminance distribution measurement as a surface illumination light source In the plate-shaped uneven thickness molded product 36 obtained by the method of (2) above, as shown in FIG. A diffusion film 52 was affixed to the opposite surface, a cold cathode tube 53 (diameter 3 mm, length 220 mm) was placed on the thick-side end surface of the molded product, and connected to an inverter to produce a surface light source illumination device. After the cold-cathode tube was lighted for 30 minutes to stabilize the brightness, the light-emitting surface was divided into 25 vertical and horizontal, and the luminance at each position was measured with a luminance meter 54 (CA-1000 type manufactured by Minolta Camera Co., Ltd.). . Each luminance value obtained was expressed as a distribution, and a luminance maximum value and luminance uniformity (a value obtained by dividing the luminance minimum value by the luminance maximum value) were derived.
[0046]
[Examples 1-4, Comparative Examples 1-2]
With the uneven shape and thickness of the metal thin plate and the installation conditions of the metal thin plate as shown in Table 1, a mold was obtained by the above methods (1) and (2), and injection molding was performed for 50 shots. During molding, the release state of the molded product was observed, and after the molding, the fixed state of the metal thin plate was confirmed. Further, the number of molding shots that could be stably molded without causing release of the molded product or peeling of the metal thin plate was measured.
[0047]
In Examples 1 and 3, the molded product was released satisfactorily in all shots, and the metal thin plate remained completely in the original fixed state even after the completion of molding, and did not change from the state before molding. Further, the number of molding shots judged to have been stably molded was 50 shots, which was a very favorable result.
[0048]
In Example 2, although a depression was generated at the position of the suction hole on the surface of the metal thin plate, it was judged that the molded product was released well up to 45 shots and could be molded relatively stably.
[0049]
In Example 4, although a dent was generated at the position of the suction hole on the metal thin plate surface as in Example 2, it was determined that the molded product was satisfactorily released up to 40 shots and could be molded relatively stably.
[0050]
In Comparative Example 1, the molds were released satisfactorily until the first two shots, but after that, they floated up from the matrix due to the thermal expansion of the metal thin plate in the vicinity of the flow end, and the molded product could not be released satisfactorily. The number of molding shots judged to be stable molding was only 2 shots, which was not preferable.
[0051]
In Comparative Example 2, in the first shot, the metal sheet floats up near the flow end portion due to the thermal expansion, causing wrinkles, and the molded product cannot be released properly and stable molding can be performed. The result was unfavorable.
[0052]
[Table 1]

[0053]
[Examples 5-6, Comparative Examples 3-4]
The evaluation of the above (3) was performed using the molded products obtained in Examples 1 and 3 and Comparative Examples 1 and 2 as test pieces.
[0054]
In Examples 5 and 6, the molded products obtained in Examples 1 and 3 were used as test pieces, respectively. In any of the test pieces, the uneven shape was uniformly transferred over the entire surface of the molded product, and the appearance state was judged as ◯, which was a very preferable result.
[0055]
In Comparative Example 3, the molded product stably obtained in Comparative Example 1 was used as a test piece. In spite of the fact that the molding could be performed stably without any defective mold release, the uneven shape was not sufficiently transferred, so that a pattern due to non-uniform light scattering occurred, and the appearance state was judged as x.
[0056]
In Comparative Example 4, the molded product obtained in Comparative Example 2 was used as a test piece. The wrinkle pattern accompanying the thermal expansion of the metal thin plate was transferred, and the uneven shape was hardly transferred, and the appearance state was judged as x.
[0057]
[Example 7, Comparative Example 5]
In Example 7, the molded article obtained in Example 1 was used as a test piece, and in Comparative Example 5, the molded article obtained in Comparative Example 1 was used as a test piece to evaluate the above (4), and the results shown in Table 2 were obtained. Obtained.
[0058]
In Example 7, the luminance maximum value was 750 nt, and the luminance uniformity was 0.72, which was a high value, and a uniform and bright surface illumination light source device could be obtained.
[0059]
In Comparative Example 5, the maximum luminance value was 340 nt, and the luminance uniformity was 0.35, both of which were low values. As a result, it was not possible to obtain sufficient performance as a surface illumination light source device.
[0060]
[Table 2]

[0061]
【The invention's effect】
By using the mold of the present invention, it is possible to arbitrarily change the pattern of fine uneven shapes as required, and industrially produce various thermoplastic resin molded products in which the uneven shapes are effectively transferred. Can be produced stably.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a shape of a suction hole constituting a mold in the present invention.
FIG. 2 is an example of a conceptual diagram of a mold in the present invention.
FIG. 3 is a configuration diagram of a mold used in an embodiment of the present invention.
FIG. 4 is an explanatory diagram of the shape and arrangement of suction holes in a mold used in an embodiment of the present invention.
FIG. 5 is a conceptual diagram of a luminance distribution measuring method of a surface illumination light source used in an example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Metal thin plate 21 Cavity part 22 Frame 23 Nest 34 which has a suction hole Gate position 35 Parting surface 36 Plate-shaped uneven thickness molded article 42 Exhaust system flow path 51 Reflective film 52 Diffusion film 53 Cold cathode tube 54 Luminance meter

Claims (3)

  On the surface of the nesting having the suction holes, a metal thin plate having a fine uneven shape is provided on the surface forming the mold cavity, and the outer peripheral portion on the resin gate portion side of the metal thin plate is sandwiched between frames, A mold for resin molding characterized by having a structure in which the resin flow end side of the other end can be moved, and a thin metal plate is installed on the surface of the insert.   2. The resin molding according to claim 1, wherein a ratio a / t between a diameter a of the suction hole in the nesting and a thickness t of the metal thin plate is in a range of 0.05 to 5. 5. Mold.   A method for molding a thermoplastic resin, wherein injection molding is performed using the mold according to claim 1.

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